import java.util.Scanner;

public class demo014 {
    public static void main(String[] args) {
        Scanner scan=new Scanner(System.in);
        System.out.println("请输入一个数");
        double a= scan.nextDouble();
        double b= 1;
        for (double i = 2; i <= a; i++) {
           b=b-1/i;

        }
        System.out.println(b);
    }
}
